The present invention relates to a reverse conducting insulated gate bipolar transistor (IGBT) and a method of manufacturing the same.
Conventional IGBTs are used, for example, in inverter circuits to regulate a load such as an electric motor. An example of such a conventional IGBT is described in U.S. Pat. No. 5,160,985, which is incorporated by reference herein. Conventional inverter circuits include conventional IGBTs, each connected in parallel to a free-wheeling diode to allow for current circulation, since a conventional IGBT has no bi-directional current flow capability.
U.S. Patent Application No. 2005/0258493, which is incorporated by reference herein, describes a reverse conducting IGBT, in which an IGBT and a free wheeling diode are monolithically formed on a substrate. The reverse conducting IGBT includes a conductive type base layer formed in the substrate and a short lifetime region formed in the conductive base layer. An emitter electrode and a gate electrode are formed on a front side of the substrate and a collector electrode is formed on the back side of the substrate. The short lifetime region is formed in the conductive base layer by irradiating the substrate with an electron or helium beam from the front side of the substrate.
U.S. Pat. No. 6,323,509 and U.S. Patent Application No. 2006/0043475, both of which are incorporated by reference herein, describe various reverse conducting IGBTs having integrated diodes.